Means for measuring and registering wind power



April 13, 1954 LANNEFORS 2,674,878

MEANS FOR MEASURING AND REGISTERING WIND POWER Filed May 11, 1950 2 Sheets-Sheet l Hg 1 I //7 Ven for Len/var? LCM f p 13, 1954 LANNEFORS 2,674,878

MEANS FOR MEASURING AND REGISTERING WIND POWER Filed May 11, 1950 2 Sheets-Sheet 2 //7 yen for Len/1a r2" La mi 15 Patented Apr. 13, 1954 MEANS FOR MEASURING AND REGISTERING WIND POWER Lennart Lannefors, Ludvika, Sweden, assignor to All Vasteras, Sweden,

manna Svenska Elektriska a Swedish corporation Aktiebolaget,

Application May 11, 1950, Serial No; 161,309.

Claims priority, application Great Britain May24, 1949 7 '7 Claims.

This'invention relates to electrical means for measuring and registering wind power.

The use of wind energy has recently become of particular interest, and in order to ascertain Whether a, particular site is suitable for the crection of a wind power station, or to compare the relative suitabilities of various sites for such a purpose, devices forv the measurement ofwvind power are in the'first place required. By means of these devices it is possible to obtain the necessaryrstatistical evidence upon which the choice of site can be. based. The measuring device, which ought to include an integrating meter, should bemade in such a way as to permit simple handling and ease oftranspcrt-from one measuring point to another. Moreover the device may be combined with a duration meter, e. g. an instrument showing the duration in hours of wind power within difierent ranges.

Usually the wind-gauge consists of a wind operated vane system, which is caused to rotate, and which, by means of a suitable member, may either generat 'a certain direct current voltage, correspondingv to the wind speed, or may convert a given voltage into a direct current voltage, varying with the windspeed.

In measuring wind energy, the device should pay regard to the known fact that the wind. power varies as the cube, or third power, of the wind speed. In order to simplify. comparison, it is suitable that the device'records the cube of the wind speed.

It is desirable that the measuring device fulfills the conditions that it shall not record wind speeds of less than a predetermined minimum valuegand -also that it should record'a constant value -when the wind speed exceeds a predeterminedmaximum value.

a rangeoflwind .powerswhicnas far as possible,

agreeswith the working range of-a modern Wind'- 1 is arranged to deliver or to generate a direct cur-- rent voltage or current, varying with- .the wind speed, which voltage or current is arranged to influence an integratiing meter, in the circuit of which an impedance element is arranged, the

traversing current of which varies according to the'same function as that according to which the'windpowervaries.

A device according to the present invention'fulfills all the requirements mentioned and thus forms a particularly suitable means for analysing windenergyat a site .duringlong or. short periods ofatimeu;

By fulfilling these re quirements; the measuring device will respond to The invention will. be. further described with: reference to the accompanying two drawings,-:. in.

which Figure 1 schematically shows an arrangement. according to the invention usinga pro-saturatedv reactor, in the following called a transductor, the. voltage of which feeds the integrating meten.

According to one definition, thetransductor dea vice consists of one or -more ferro-ma'gnetic; cores with windings by means of which an. ale.. ternating current .voltage. or current can bevaried by a voltage or current utilizing: saturation phe-:

nomena on the core material.

Figure2 shows a complete-diagram of a form.

Figure 5 showsa further diagramof a form ac cording to the invention.

In'all figures. corresponding items: are designatedby the same reference numerals.

In all figuresthe reference numeral. I is used for'the wind-gauge converting. the wind: speedinto a direct current voltage. A suitable form of the wind-gauge is described inv the'fiASEA Journal 1 :1948 ially Fig. .6 (page .41) 1 copies of which journal may be seen at the National Bureau of Standards, Washington, D. C.,.and at the Engineering. 22 West 39th Street, New York;-

ciety Library,

New York,.and elsewhere in U. S. A., and which wind-gauge consists .of a member. connected. to an existing electrical network at 2, containing; the above-mentioned vanesystem, whichrduring its rotation alternatively short-circuitsa number of condensers which charged by a constant directcurrent voltage de.-. rived fromthe network 2 ternating or direct current. voltage. When short-circuited, the condensers are discharged, and a direct current voltage may thus be obtained; suitably arranged: corn 1 ductors. 1 This voltage will beproportional to the.

from the device through frequency of the movementsof the short+cir.-

not exclude the use of' other members for the same purpose, such as generatorsand'the'like;-'

Figure 1 shows diagramaticallya simplified ar-- March-April, pages 39-42 espec-=w have been previously which may supply al rangement according to the invention, using a transductor as the non-linear impedance element. In this form, no regard is paid to the limitation of the operating range which may be accomplished in any way, some of which are shown in the other forms. In this figure, the direct current voltage delivered from the windgauge l is impressed upon an excitation winding of a transductor, the alternating current, or in this case voltage, of which is supplied to the in-- strument. The transformer 10, the primary terminals ll of which are connected to an alternating current line, has two secondary windings l2 and [3. The winding I2 is connected to the alternating current winding of a transductor H, the transductor being drawn according to a conventional symbol. In series with the transductor a resistor and an iron filament lamp it are inserted. The transductor symbol shows self-excitation (compare the Patent 2,455,869), preferably arranged as spare-self-excitation (compare the Patent 2,470,556) in order to increase the sensitivity, indicated by the arrow II, which arrow also indicates the necessary direction of the current in the other excitation windings to give an increase of the output from the transductor. The transductor is provided with a certain pro-excitation by the winding ill, the current of which is supplied by the winding it of the transformer I!) through a rectifier 19. A

resistor is inserted in series with the winding 18 as a means of adjusting the current in said winding. The current of the winding l8 cooperates with the self-excitation. The windgauge is supplying a voltage to an opposing excitation winding 2l. The voltage across the transductor is after rectifying in the rectifier 22 delivered to the ampere-hour meter 4 in series with which a resistor 23 is connected.

By the pre-excitation, the transductor is made to operate at the lower bend of its characteristic curve at small wind speeds. With increasing wind speeds, the transductor operates at points according to the ascending characteristic curve, giving a voltage across the transductor which thus substantially follows the wind power. The iron filament lamp l6 serves as a current stabilizer in the transductor circuit. The lower limit may be obtained by fitting the ampere-hour meter with known means for magnetic blocking which releases the rotating member of the instrument when a certain current passes through it.

In Figure 2, 24 is the primary winding of a transformer, connected to an alternating current line at l l. The transformer is provided with three secondary windings 25, 26, 21. To the winding 26 a circuit is connected containing in series a transductor 28 and a rectifier 2s. The latter supplies direct current for the integrating meter, consisting of an ampere-hour meter connected in series with a resistor 23. The rectifier also provides self-excitation by means of the control winding 30 of the transductor connected to it. The transductor may, as described above, profitably be fitted with means for spare-self-excitatioh indicated by the arrow. The winding 30 is co-operating with that spare-self-excitation. Th current through the winding 30 may be adjusted by the resistor 3|. The excitation winding 32 of the transductor which opposes the before-mentioned windings is fed from the secondary winding 25 over the rectifier33 and the adjustable resistor 3A. A further winding, co-operating with the winding 32,

is denoted by 35. This winding is in series with a resistor 36 and a current valve 31 traversed by a current forming the difference between a constant comparison current obtained from the transformer winding 2'1, rectified by the rectifier 38, and smoothed by the condenser 39, and the current from the wind-gauge I. To adjust the currents in the circuits two resistors 40 and 4| are inserted.

The last mentioned arrangement of the excitation winding 35 allows the ampere-hour meter 4 to register as at constant wind speed for wind speeds above the upper limit of the range. The valve element is so connected as to block the excitation circuit 35 when the current from the wind-gauge l exceeds the constant comparison current. When the excitation winding 35 is blocked, the magnetisation of the transductor is only determined by the constant current through the winding 32. If the wind speed falls below that upper limit, the current through the winding 35 will vary linearly to its maximum value which is attained at a wind speed equal to zero. The current through the windings 35 b will then bring down the magnetisation of the transductor to its minimum value, and the load current will be diminished according to the shape of the characteristic curve.

In order to make the transductor operate within the desired part of its characteristic curve, it may be provided, as mentioned above, by one or several magnetising windings. The shape of the transductor curve may be influenced, e. g. by altering the degree or mode of smoothing of the excitation current, by varying the alternating current voltage in the transductor cirsuit or by varying the degree of self-excitation. The lower bend of the characteristic curve may be altered by these means in a desired manner, as well as the steepness of the ascending part of the curve.

In Figure 3, the function between the excitation current (the abscissa) and the load current traversing the transductor (the ordinate) is illustrated. The arrow it indicates the constant pre-excitation through the winding 32 (Figure 2) and b represents the current through the winding 35, at full length of the arrow 2), depending only on the constant comparison current from the rectifier 38. The load current varies from the point e at the lowest wind speed, i. e. no current from the wind-gauge I, to the point i at full wind speed, i. e. full current from the windgauge.

By using a form of the invention according to Figure 2, some difiiculties will arise to obtain a discontinuous change at 1 from the transductor curve to the horizontal line. If a more definite following of the ideal curve is desired, the device may be constructed, for instance, according to the scheme in Figure 4.

In Figure 4, the primary winding 42 of a transformer is connected to the line at II. The transformer is provided with four secondary windings 43-46. To the winding 44 is connected in series a transductor 4'1 and a rectifier 48. The latter feeds the instrument i in series with the resistor 23. In that circuit a contact 49 of a relay 5!) is inserted by means of which the above mentioned lower limit of the operating range is controlled, as will be described hereinafter. The rectifer 48 also feeds a self-excitation winding 5| of the transductor'in series with a resistor 52.

The transductor is provided with an additional winding 53 co-operating with the winding 51 with the resistor 61.

acc sses and'com'rected totheterminals ofthe wind-gauge inseries with a contact 54 of a voltage responsive relay 55-: The relay coil is also-connected to the wind-gauge; Another excitation winding-51, opposingthe other; is connected to thetransformer winding 43-over the rectifier 58; Normallya resistor 59 in that excitation circuit; is short-circuited by the contact 55 of the same relay 55.

The lower limit relay-Wis fed through a trans-- ductor amplifier 50'. nected tothe transformer winding 46 in series with the rectifier G'I' from-which the-rectified load current issupplied-to therelay coil 50: To obtain highest sensitivity; the transductor is spareself-excited"and provided with an additional self excitation by means of the winding 62, connected to therectifier 6| in'series' with the resistor 63. A co-operating excitation isob'tained by the winding 64 connected gauge.-- An opposing excitation is provided. by the winding 65 fed from the rectifier 66 in series That rectifier is connected to the transformer winding 45.

By means of the transductor amplifier 60, the small current supplied from the wind-gauge especially at weak winds is amplified, and at a certain wind speed the relay 5!: is caused to close its contact 49. At wind speeds within the operating range of the instrument 4, the transductor 41 supplies a current to it which follows the desired cubical curve. The eifect of the excitation windings is shown in Figure 3. The arrow 0 indicates the constant pre-excitation by the winding 51 in case that the resistor 59 is short-circuited. The opposing excitation represented by the arrow 11 is obtained by the winding 53 from the voltage varying with the wind speed. At g, the relay 50 closes its contact 49, and at ,f, the upper limit is reached and it is then desired that the instrument should record a constant value for exceeding wind speed. This is achieved by the voltage responsive relay 56 which, at a certain wind force, at f, breaks the excitation circuit containing the winding 53, and breaks the shortcircuiting of the resistor 59 which causes the excitation through the winding 51 to be diminished from the value c to a value corresponding to the arrow a. This value is independent of Wind speeds above the upper limit, but at lower wind speed the relay 56 will close the contacts 54, 55 and the instrument will record again according to the transductor curve.

The last form, shown in Figure 5, shows a modification as to the arrangement of the relay for the upper limit. In the figure, the transformer 68 is fed by the line at H and is provided with three secondary windings 69, 10, 1|. To the winding 69 are connected in series the transductor l2 and the rectifier 13 which feeds two circuits, one containing in series the instrument 4, a contact of a relay 14, the coil of said relay 14 and a resistor 23, and the other the selfexcitation winding 11 of the transductor in series with the resistor 18. By the same reasons as mentioned before, the transductor is preferably space-self-excited. The voltage varying with the wind speed is directly supplied to the cooperating excitation winding 19 from the windgauge l which in its turn is connected to the line at 2. A pre-excitation is obtained by the winding 80, opposing the self-excitation windings and connected to the rectifier 8| in series with the resistor 82. The rectifier is connected to the transformer winding 10. The same rectifier is also used for a special purpose which The transductor is con-- to the terminals of the wind-- may be-l-explained iin 'theisimplestuwayaasi airlin placement-of the axis of abscissae in' order'ito allow the registering of weak wind forces. 1 For; this-purposemthe rectifier is connected. through... the adjustable resistor 83 to the: instrument such: a waythat the current": fromcthis rectifier: opposes the current from the transductor- The iupper limit of .the operatingrangeiisr'cone trolledby: the current responsive relay. 14 which; at'a certain wind: speedoperates itscontacts; and bymeans of the contact 15, disconnectsi and bridges the-instrument-4, and by means: of the contact 16- atthe' same time connects the: instm-l ment to the constant voltage source:represented: bythe rectifier 8 1 which is connected to the"trans.--1 former; winding 1|." For adjusting the current; aresistor 85 'is inserted. In this waythe' in' strumenti will procure a constant recording foi forces: above the upper limit.

According to I this form ofthe inventiomthe lower limit may: conveniently be controllediby ablocking. device 1 at (the instrument.

I claim as my invention:

1. A device for measuring and registering wind power, comprising a rotating wind driven vane system, a direct current generator coupled to said system, a transductor, an alternating current source feeding said transductor, a control winding for said transductor, means connecting said control winding with said generator, an integrating meter connected with the transductor, said transductor being so dimensioned and constructed as to change its traversing current in function of the current through said control winding according to the same function as the wind power varies with the wind speed.

2. A device according to claim 1, comprising means whereby the said transductor is selfexcited.

3. A device according to claim 1 in which the said integrating meter is connected in parallel with said transductor.

4. A device according to claim 1, comprising means for blocking the said meter until there passes therethrough a predetermined current corresponding to a wind speed above a certain limit, and means for disconnecting the meter from the transductor when a current has been reached corresponding to an upper wind speed limit and for connecting it to a source of constant current.

5. A device for measuring and registering wind power, comprising a rotating wind driven vane system, a direct current generator coupled with said system, a transductor, an alternating current source feedingsaid transductor, an integrating meter supplied by the current through the transductor, said transductor being adapted to change its traversing current in function of the current through said control winding according to the same function as the wind power varies with the wind speed, a source for delivering a constant current, said source being connected in series with said generator, a control winding for said transductor being connected across the terminals of said generator, and a valve inserted in series with said control winding, said valve being adapted to block when the current from said generator has a tendency to exceed the current from said constant current source.

6. A device for measuring and registering wind power, comprising a rotating wind driven vane system, a direct current generator coupled to said system, a transductor, an alternating current source feeding said transductor, an integrating meter supplied by the current through said transductor, a control winding for said transductor being connected to said generator, means for limiting the current through said transductor when the wind speed exceeds a predetermined value, comprising another control winding on said transductor, a current source for feeding the last mentioned control winding, a resistor connected in series with the last mentioned control winding, a voltage relay connected to said generator, two contacts operated by said relay, one of said contacts being arranged to disconnect the first mentioned control winding at a voltage corresponding to said predetermined wind speed, and the other contact being arranged to break a short-circuit of said resistor at the same time, the transductor being so dimensioned and constructed as to change its traversing current in function of the current through said control winding according to the same function as the wind power varies with the wind speed.

'7. A device for measuring and registering wind power, comprising a rotating wind driven vane system, a direct current generator coupled to said system, a transductor, an alternating current source feeding, said transductor, a control winding of said transductor being connected to said generator, an integrating meter connected to said transductor, a constant current source, and a current relay inserted in series with the integrating meter, the said relay being provided with two contacts, one of which is arranged to disconnect said integrating meter at a current corresponding to a predetermined wind speed and to bridge said integrating meter, and the other contact being arranged to connect said instrument to said constant current source.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Lubowsky Oct. 16, 1928 Number 

